DTA

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Tesi etd-02222021-155700

Type of thesis
Corsi integrativi di II livello
Author
QUAGLIERINI, JACOPO
URN
etd-02222021-155700
Title
Mechanics of tubular helical assemblies: ensemble response to axial compression and extension
Structure
Cl. Sc. Sperimentali - Ingegneria
Course
INGEGNERIA - INGEGNERIA
Committee
relatore Prof. ODDO, CALOGERO MARIA
Relatore Prof. DE SIMONE, ANTONIO
Relatore Dott. LUCANTONIO, ALESSANDRO
Membro Prof. CIARAMELLA, ERNESTO
Membro Prof.ssa LASCHI, CECILIA
Membro Prof.ssa MENCIASSI, ARIANNA
Membro Prof. AVIZZANO, CARLO ALBERTO
Membro Prof. FRISOLI, ANTONIO
Keywords
  • Computational Mechanics
  • Ensemble response
  • Helical assemblies
  • Kirchhoff rod
  • Sadowsky ribbon
Exam session start date
23/03/2021;
Availability
parziale
Abstract
Nature and technology often adopt structures that can be described as tubular helical assemblies. However, the role and mechanisms of these geometries remain elusive. <br>We studied the mechanical response under compression and extension of a tubular assembly composed of 8 helical Kirchhoff rods, arranged in pairs with opposite chirality and connected by pin joints. To do this, an analytical model of the assembly based on quaternions was developed and then implemented in COMSOL Multiphysics.<br>We first focused on compression and found that, whereas a single helical rod would buckle, the rods of the assembly deform coherently as stable helical shapes, wound around a common axis. We then investigated the response of the assembly under different boundary conditions, noticing the emergence of a central region where rods remain circular helices.<br>Secondly, we studied the effects of different hypotheses on the elastic properties of rods, i.e., stress-free rods when straight versus when circular helices, Kirchhoff&#39;s rod model versus Sadowsky&#39;s ribbon model.<br>Our findings highlight the key role of mutual interactions in generating a stable ensemble response that preserves the helical shape of the individual rods, shedding some light on the reasons why helical shapes in tubular assemblies are so common and persistent.<br>
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